Sleep spectral power correlates of prospective memory maintenance

Prospective memory involves setting an intention to act that is maintained over time and executed when appropriate. Slow wave sleep (SWS) has been implicated in maintaining prospective memories, although which SWS oscillations most benefit this memory type remains unclear. Here, we investigated SWS spectral power correlates of prospective memory. Healthy young adult participants completed three ongoing tasks in the morning or evening. They were then given the prospective memory instruction to remember to press “Q” when viewing the words “horse” or “table” when repeating the ongoing task after a 12-h delay including overnight, polysomnographically recorded sleep or continued daytime wakefulness. Spectral power analysis was performed on recorded sleep EEG. Two additional groups were tested in the morning or evening only, serving as time-of-day controls. Participants who slept demonstrated superior prospective memory compared with those who remained awake, an effect not attributable to time-of-day of testing. Contrary to prior work, prospective memory was negatively associated with SWS. Furthermore, significant increases in spectral power in the delta-theta frequency range (1.56 Hz–6.84 Hz) during SWS was observed in participants who failed to execute the prospective memory instructions. Although sleep benefits prospective memory maintenance, this benefit may be compromised if SWS is enriched with delta–theta activity.

Prospective memory refers to the maintenance, retrieval, and execution of a previously formed intention (Einstein and McDaniel 1990). Successful prospective memory is essential for a large number of tasks in daily life, such as remembering to attend a doctor''s appointment, to pick up a prescribed medication after that appointment, and to also pick up other needed items (e.g., groceries) while at the drugstore. The above described hypothetical sequence of events integrates previously studied prospective memory variants including time-based (i.e., maintaining a memory to complete an intention at a prespecified time; e.g., Esposito et al. 2015; Occhionero et al. 2017), activity-based (i.e., maintaining a memory to perform an intention before or after a particular activity; e.g., Occhionero et al. 2020), and cue-based (i.e., relying on external cues to prompt a maintained memory for a set intention; e.g., Scullin and McDaniel 2010; Leong et al. 2019b; Scullin et al. 2019).When it is required that memories be maintained across longer periods of time, prospective memory may become less reliable unless sleep occurs (Scullin and McDaniel 2010; Diekelmann et al. 2013a,b; Grundgeiger et al. 2014; Leong et al. 2019a,b; Scullin et al. 2019). Sleep appears to most strongly aid spontaneous retrieval of cue-based prospective memories (Leong et al. 2019a). Several reports have found that slow wave sleep (SWS) supports spontaneous retrieval of cue-based prospective memory intentions (e.g., Diekelmann et al. 2013a; Leong et al. 2019b), although at least one study found an association with rapid eye movement (REM) sleep instead (Scullin et al. 2019). Cue-based prospective memory is hypothesized to be a type of associative memory that binds prospective components (the prospective memory cue) and retrospective components (maintenance of the memory for the prospective memory intention when presented with the cue; Diekelmann et al. 2013b; Leong et al. 2019a).Rodent and human literature, implementing a variety of invasive and noninvasive brain imaging techniques, show that cortical slow oscillations (SOs; <1 Hz) and fast thalamocortical sleep spindles during SWS facilitate associative memory retention (Niknazar et al. 2015; Latchoumane et al. 2017; Helfrich et al. 2018; Mikutta et al. 2019; Muehlroth et al. 2019), whereas faster oscillations, such as those in the theta frequency band (∼4–7 Hz), may inhibit declarative associative memory (Marshall et al. 2011). We therefore hypothesize that prospective memory performance, like other studied associative memory variants, should benefit from oscillations during SWS (Klinzing et al. 2019). However, it remains unknown which SWS microarchitectural features may facilitate or inhibit prospective memory performance.Here, we aimed to first replicate prior findings that prospective memories are better maintained across a 12-h interval including sleep compared with an equivalent interval of wakefulness (e.g., Scullin and McDaniel 2010). We next explored whether sleep-associated memory maintenance might be linked to SWS microarchitectural features. To our knowledge, this is the first experiment to examine whether SWS oscillations differentiate successful from unsuccessful prospective memory performance. Given the role of hippocampal engagement in both associative memory binding (e.g., Yonelinas et al. 2019) and oscillatory coupling during SWS that supports associative memory (Niknazar et al. 2015; Latchoumane et al. 2017; Helfrich et al. 2018; Mikutta et al. 2019; Muehlroth et al. 2019), we hypothesized that prospective memory performance would be supported by SWS and specifically SOs and sleep spindle activity.     

Because I want to share,not because I should: Prosocial implications of gratitude expression in repeated zero-sum resource allocation exchanges

Motivation and Emotion - The current research examines how gratitude (vs. neutral) expression indirectly reinforces prosocial resource-allocation decisions in repeated zero-sum social exchanges....     

The concept of reflection: a systematic review and thematic synthesis across professional contexts

Reflection is widely endorsed by professional bodies and practitioners are required to document professional learning to evidence standards of professionalism. Due to the lack of a consensual definition for reflection, there is confusion regarding ‘what reflection is’. Prior to the development of an empirical evidence base that explores reflection, it is important to develop a consensually agreed concept and definition to guide experimental research. The aim of this systematic review is to understand the concept of reflection by performing a synthesis of existing conceptually oriented qualitative studies. Fourteen sources were included in a thematic synthesis that resulted in the construction of four analytical themes: cognitive, integrative, iterative and active. These themes were explored in relation to existing research and a novel definition of reflection was proposed. It is hoped that this review will encourage further enquiry into the concept and process of reflection.     

Unconscious color priming occurs at stimulus- not percept-dependent levels of processing

Although past studies have shown that visual information can be processed without awareness, the types and levels of this processing have yet to be determined. We used metacontrast masking to explore unconscious priming effects of white, blue, and green stimuli generated on a color video display. We found that a white prime tends to act more like a green than a blue one. Color confusions among unmasked and masked primes and calibrations of the display phosphors show that physical rather than perceptual properties of the stimuli best explain the white prime's effects. We conclude that unconscious color priming in normal observers occurs at early wavelength-dependent levels of processing prior to later color-percept-dependent levels.     

A semi-persistent adult ocular dominance plasticity in visual cortex is stabilized by activated CREB

The adult cerebral cortex can adapt to environmental change. Using monocular deprivation as a paradigm, we find that rapid experience-dependent plasticity exists even in the mature primary visual cortex. However, adult cortical plasticity differs from developmental plasticity in two important ways. First, the effect of adult, but not juvenile monocular deprivation is strongly suppressed by administration of barbiturate just prior to recording visual evoked potentials, suggesting that the effect of adult experience can be inactivated acutely. Second, the effect of deprivation is less persistent over time in adults than in juveniles. This correlates with the known decline in CREB function during maturation of the visual cortex. To compensate for this decline in CREB function, we expressed persistently active VP16-CREB and find that it causes adult plasticity to become persistent. These results suggest that in development and adulthood, the regulation of a trans-synaptic signaling pathway controls the adaptive potential of cortical circuits.     

Mapping Variables Related to Social Identity,Distress and Perceived Health in an Undergraduate Student Population

The relationship between students levels of self-categorisation or identification with their university, their problem-solving style, perceived social support, psychological distress and self-reported illness was investigated in a sample of 269 students (181 females and 88 males). Structural equation modelling shows that problem-solving style, perceived social support, and strength of identity, are the best predictors of both distress and illness, while sex, sex-type, age and year of study also account for small, but significant percentages of the variance.     

Child sexual abuse: offenders,disclosure, and school-based initiatives

Children are being sexually abused at an alarming rate. Prevalence estimates suggest that one out of four girls and one out of ten boys experience sexual abuse. This paper examines the devastating impact of child sexual abuse and explores the contributions of school-based interventions to remedy the problem.     

Attitudes toward illegal immigration: a cross-national methodological comparison

This research is an examination of the generalizability of a Likert-type scale originally devised to measure attitudes toward illegal immigrants (IA) in the United States. The current authors administered this scale across 4 national samples using several methodological procedures. Undergraduate students (631) responded to the IA scale (R. Ommundsen & K. S. Larsen, 1997) at the University of Oslo, Oregon State University, the University of Copenhagen, and Vrije University of Amsterdam. The authors' main purpose was to evaluate the adequacy of the 20-item IA scale by examining possible problems with method and translation. A translation study carried out with the Danish, Norwegian, and Dutch samples (N = 299) showed that the various national versions were fairly accurate and contained largely the same meanings. The use of procrustes analysis of the IA scale yielded 3 factors in all 4 national samples. The coefficient of congruence of these 3 orthogonally rotated factor matrices, with the U.S. factor matrix as target, varied from .80 to .95, supporting the cross-national robustness of the scale. In the search for a more economical cumulative scale, a Mokken analysis yielded a 5-item scale that represented the aforementioned 3 factors and was stable across national samples.